Color television tube



April 8, 1967 B. R. WINGE 3,315,027

COLOR TELEVIS ION TUBE Filed Dec. 13, 1963 R G B R G B R 25 23 B R c; aR a R R k R 24- B 5 B INVENTOR.

BERNICE l2. WINGE 37 BY 7 ATTORNEY 2 Sheets-Sheet t United States Patent-Ofitice 3,315,027 COLQR TELEVISION TUBE Bernice Ray Winge, 39 E. SurreyDrive, Charleston Heights, 8.0 29405 Filed Dec. 13, 1963, Ser. No.330,283 4 Claims. (Cl. 178-54) This invention relates to an improvedpicture tube especially adapted to color television, and compatible toblack and white reception. The improved tube may be used with colortelevision receivers on the market in conjunction with the circuitryshown as part of this invention. The invention is especially useful inpicture tubes having a single electron gun, but has other applications.

In the present system, commonly called the Tri Dot system, a battery ofthree electron guns are so positioned that their beams converge at 60degree angles through tiny apertures placed directly in front of thescreen. On the screen proper, and placed in proper geometric relation,are three dots of phosphor, representing three primary colors; red, blueand green, at which the beams are aimed. Each electron gun must be aimedat its respec tive color, and a high degree of accuracy must bemaintained for proper operation. To maintain thi accuracy, or properconvergence, many complex electronic circuits and critical positioningof elements are necessary. Even so, only a small portion of theelectrons penetrate the apertures, resulting in relatively lowefiiciency, and necessitating higher currents and voltages from thepower supplies. Another serious shortcoming of the present three guntube is its susceptability to magnetic fields, requiring special shieldsand components which are often ineffective should the receiver be movedto a different location. Still further, the neck of such present tube islarge, requiring a special yoke design, and high currents.

Therefore, an important object of this invention is to eliminate theproblem of convergence by providing an improved single gun colortelevision tube capable of practical operation.

Another object of this invention is to provide a more eflicient colortube requiring lower voltages and currents, and using less components ofsimpler design.

Another important object is to greatly lessen the susceptibility of acolor tube to magnetic fields, including the earths magnetic field, andreduce the requirements for special shields, magnets, coils and thelike.

Still another object of the invention is to produce a tube of a singleneck design permitting the use of smaller yokes, thus relieving furtherthe load on the power supply, through a tube of relatively simpledesign.

Anotherimportant object of this invention is to provide a tube affordinga greater degree of color purity across the entire scan.

Still another object of this invention is to provide the user of thetelevision set a simple and easy device to operate.

The construction designed to carry out the invention will be hereinafterdescribed, together with other features thereof.

The invention will be more readily understood from a reading of thefollowing specification and by reference to the accompanying drawingsforming a part thereof, wherein an example of the invention is shown andwherein:

FIGURE 1 is a schematic side elevation illustrating a tube, togetherwith a block schematic diagram illustrating electronic componentsconstructed in accordance with the present invention.

FIGURE 2 is an enlarged elevation illustrating the first molded plateand grid assembly, and

FIGURE 3 is an enlarged elevation illustrating the 3,315,027 PatentedApr. 18, 1967 arrangement of the phosphor color dots and the secondmolded plate. I

Referring now to FIGURE 1, the tube bell portion 71 has a neck 74) and aviewing screen 6. An electron gun including a heater 1, a cathode 2, acontrol grid 3, and

statically focus the electron beam 28, acceleration voltage on thecoating 10 and a deceleration voltage on the coating 13. The electronbeam will ultimately arrive at the face or" the viewing screen 6, but inso doing will pass through the holes in the first molded plate 20, whichhas a conductive coating 21 on the front side thereof. The coating 21 isconnected to a suitable voltage source 74 to further control the beam 28adjacent the plate 24 The beam will also pass through the color gatinggrids 22, 24 and 26, the holes in the second molded plate 39, and willstrike the appropriate color dots 32, 34 and 36. The conductive coating21, molded plate 20, color gates 22, 24 and 26, molded plate 30 and thecolor dots 32, 34. and 36 are sandwiched together in register, but areshown schematically as an exploded view for purposes of illustration.

Referring to FIGURE 2, it will be noted that the holes are preferablyoctagonal in shape to permit maximum penetration by the electron beam.The side of the plate facing the electron gun has a conductive coating21 to conduct away the electrons that fail to enter the holes. FIGURE 2shows the molded plate 24 illustrating a preferred arrangement of thecolor gating grids 22, 24 and 26 with respect to the insulating materialof the plate 20. The color gate grids may be of an extremely fine wiremesh inserted in the holes 22, 24 and 26 woven with 500 to 1,000 endsper inch, such as the grid used as a shadow mask in the iconoscope, ormay be deposited on the inside surfaces of the holes. The grids aredivided into three groups in the pattern shown in FIGURE 2 with properelectrical connections. The grids marked R (red) in FIGURE 2 areterminated at 23, the grids marked B (blue) are terminated at 25, andthe G (green) grids are terminated at 27. The color signals from thetelevision receiver will be applied to the conductors 23, 2'5 and 27 ina specific manner to be fully discussed below.

It will be noted that any electrons arriving at the plate 20 from thebeam 28 must enter the holes and pass through the influence of the colorgating grids 22, 24 and 26. It will also be noted that the respectiveholes also designated R, B and G are positioned in a specific manner ina triangular sequence. The electron beam 28 will be focused so that itwill scan two horizontal lines of holes at a time (such as line A andline B in FIGURE 2), and will cover an area defined by three holes (suchas holes X, Y and Z, FIGURE 2). The electron beam 28 will traverse theholes from left to right in FIGURE 2 so that as the beam 28 leaves ahole, it will pick up another hole of the same color.

Situated directly in front, and in register with molded plate 20 is asecond molded plate 30 constructed of insulating material. Theconstruction of molded plate 30 .3 is illustrated in FIGURE 3. Referringto FIGURE 3, it will be seen that the bottoms of the holes of plate arefilled with phosphor 32, 34 and 36, respectively. The color of thephosphor agrees with the arrangement of color holes as shown, that is,all R holes are filled at the bottom with red phosphor 32, all B holeswith blue phosphor 34, and all G holes with green phosphor 36. Thebottom of the holes in FIGURE 3 constitute an integral part of the faceof the viewing screen.

Thus, a picture tube is constructed in a conventional manner as regardsthe envelope and the electron gun, and is operated as a conventionalcathode ray tube. A color gating-system of electrodes near the face orscreen of the tube is also provided. Electrons arriving from the beam 28to the color gating system will be forced to enter a hole to reach aphosphor dot. Once an electron enters a hole, it is trapped so as toeliminate color spreading. After electrons enter a hole, and before theyarrive at the phosphor, they must pass through a color gating grid (22,24 or 26) where they may be diminished in number, or completely stopped,depending upon the value of the gating voltage in relation to the colorsignal, which is supplied by the receiver according to the requirementsof the picture transmitted.

Another very important consideration is the control of the quality ofcolor reproduction. Referring again to FIGURE 1, it will be noted that astandard Y signal is applied to the cathode. The Y signal is takendirectly from the receiver and is used to control the density of theelectron beam 28 and hence the brightness of the picture. In colortelevision circuits this signal is often referred to as the black andwhite component. The voltage of the Y signal is a function of thecombined amplitudes of the incoming signals, and will vary the densityof the electron beam 28 accordingly. When the electron beam is projectedtoward the screen in various densities, due to multiple colorsincreasing or decreasing the Y signal, it is desirable that the gatinggrids 22, 24 and 26 compensate for the changes in density to maintaintrue color reproduction. The electron flow through a control gridincreases if the incoming electrons increase in number, even though thebias on the grid remains constant. Therefore, an increase in the Ysignal due to the addition of multiple color signals, for example, wouldincrease the intensity of all the colors reproduced due to an increasednumber of electrons reaching the screen, thus distorting the colors. Thefollowing discussion describes a solution to this problem in accordancewith the invention.

Referring again to FIGURE 1, the arms of potentiometers 46, 47 and 48are connected to the three color grids 26, 22 and 24 through resistors52, 54 and 53. The potentiometers 46, 47 and 48 are so adjusted as toprovide a standard relative bias on the color grids so that the red grid22 is biased, for example, at 30%, the blue grid 24 at 11% and the greengrid 26 at 59%. In the absence of any color signal, the three grids willcontrol electrons in this percentage, and compatible black and whitewill be produced. The potentiometers 46, 47 and 48 are in effectcontrast controls.

It will be noted that the potentiometers 55, 56 and 57 are common to oneside of a high voltage supply, and supply the phosphor color dot groups32, 34 and 36, respectively, through leads 33, 35 and 37. The purpose ofthe potentiometers is to adjust for the sensitivity of the particularcolor phosphor and produce exact color hues. These potentiometerscorrespond to the brightness controls on conventional television sets.

Assuming, for example, that a single color, red, is received. The redsignal will appear simultaneously at the input of the Y amplifier 12 andthe R amplifier 14. The Y amplifier 12 will amplify and invert thesignal and apply it to the cathode as a negative going signal. Thecontrol grid is held at a proper bias by power supply 3a to keep thepicture tube in conduction. The negative going Y signal will increasethe electron stream 28 from the single electron gun assembly, and thedensity of the electron stream will be proportional to the appliedvoltage from the Y amplifier 12.

The red signal is also applied to the input of the R amplifier 14 andreceives normal amplification. It is taken out as a negative goingsignal and applied to the input of R controlled amplifier 1411. Hereagain, it receives normal amplification, and is taken out as a positivegoing signal fed through the conductor 23 to the red color grids 22,driving them positive. The R signal is also applied to the R amplifier58. Here it is amplified and fed as a negative going signal to a matrixarrangement including the resistors 39, 40, 41 and 42. The matrix systemis calculated so as to proportionately feed the succeding amplifiersaccording to the color optical ratio, stated as red 30%, blue 11% andgreen 59%. The output from the resistors 39 and 40 operates a matrixbias generator 62 which passes the signal to bias down the G (green)controlled amplifier 16a by lead 68. This may be accomplished byapplying the signal to the screen grid of the amplifier 16w or to asecond control grid. Thus, the output of amplifier 16a normally fed tothe green color grids 26 by lead 27 is greatly reduced.

Also, the output of matrix bias generator 62 is fed by the lead 65 tothe potentiometer 44. From the arm of the potentiometer the output isfed through the capacitor 50 to the green color grid 26. Since theoutput is a negative going signal, it will also bias down the greensignal. Thus, the green phosphor is blanked, and will not light. Theoutput from the R amplifier 58 is applied to the matrix amplifier 63through matrix resistors 41 and 42 producing a negative signal appliedto the B (blue) controlled amplifier 15a through lead 69 to reduce itsgain. Thus, the output of B controlled amplifier 15a, normally fed tothe blue color grids 24 by lead 25, is greatly reduced. The signal isapplied to the potentiometer 45 through lead 66. The signal is takenfrom the arm of the potentiometer 45, passed through the capacitor 49and fed to the blue color grid 24 to bias it out of conduction. Thus, itis seen that when a particular color appears alone, it Will turn on itscolor amplifiers, and cut oft" the other two color amplifiers. The abovediscussion for red, applies similarly for each of the other two colors.

Consider now the action of the circuits when two color signals, red andblue, for example, are received. The Y signal is increased in accordancewith the addition of R and B signals, and the density of the electronbeam 28 increases correspondingly. Since more electrons would normallyarrive at the red color grid 22, the red would deepen. This is whatpresently distorts the colors in color picture tubes. Referring again toFIGURE 1, as the B signal is added to the Y amplifier 12 and the Bamplifier 15, it is at the same time added to the B amplifier 60. Theoutput of B amplifier 60 is matrixed through resistors 37 and 38 to thematrix amplifier 61 and the negative going signal from matrix amplifier61 used to bias down the red amplifier 14a by lead 67. Also, the outputof matrix bias amplifier 61 will bias down the red color grid 22 throughlead 64, through potentiometer 43, and from the arm of potentiometer 43through capacitor 51 to the red color grid 22. Since the decrease inintensity of the red signal is proportional to the increase of Y signal,the red color is returned to its natural hue.

It will be noted that the red signal was present when the blue signalwas added", therefore, the blue color grids 2 Were observing both redand blue signals, and to produce a proper blue color must discount thered signals present in beam 28. Referring again to FIGURE 1, the Rsignal was simultaneously applied to R amplifier 14 and R amplifier 58.The R amplifier 14 amplified and inverted the signal and applied it tothe grid of R controlled amplifier 1411. R amplifier 58 amplified andinverted the signal and applied it through the matrix resistors 41 and42 to matrix amplifier 63. A negative going signal was taken fromamplifier 63 and fed to the second control grid of B controlledamplifier a to reduce the blue signal. For further color control (may beadjustable on a panel by the operator) the blue may be balanced bypotentiometer 45, which is connected to the matrix amplifier 63 by thelead 66, and further connected to B color grid 24 by the capacitor 49.

Thus, each color signal will matrix the other colors, as they deepen dueto the increase of Y signal as other colors are added. In theconsideration of three colors, from which all colors Will be obtained,the above discussion may be expanded. In this connection, it will henoted that green amplifiers 16 and 59 are provided. It will be seen thatany one color will diminish the other two proportionally to the increaseof Y signal. The redoctions of the signals will be controlled partiallyat the screen grids of the controlled amplifiers 14a, 15a and 16a. Thus,the reduction is made at two points; at the screen grids of thecontrolled amplifiers and through potentiometers 43, 44 and 45.

While a preferred embodiment of the invention has been described usingspecific terms, such description is for illustrative purposes only, andit is to be understood that changes and variations may be made withoutdeparting from the spirit or scope of the following claims.

What is claimed is:

1. In a color television circuit and image tube having a single electronbeam, an image screen, a plurality of control electrodes controllingelectron flow to the image screen responsive to each color signal, theimprovement including, amplifying means, for amplifying each colorsignal individually, a controlled amplifier receiving each amplifiedsignal, matrix bias means receiving each amplified signal and applyingsame to the controlled amplifier of each other color signal, and meansconnecting the controlled amplifier output signals to the colorelectrodes within the tube.

2. The circuitry set forth in claim 1 including, means connecting theoutput signals of the matrix bias means to the color electrodes withinthe tube.

3. The method of applying a bias to the color electrodes of a colortelevision image tube .having at least one electron beam and an imagescreen including, amplifying each color signal individually, applyingeach such amplified color signal to a controlled amplifier and to matrixbias means wherein a specific signal results in the diminution of theother color signals, applying the output of the matrix bias means torespective controlled amplifiers, and applying the output of thecontrolled amplifiers to the respective color electrodes.

4. In a color television circuit and image tube having at least oneelectron beam, an image screen, a plurality of control electrodescontrolling electron flow to the image screen responsive to each colorsignal, the improvement including, first means amplifying each. colorsignal individually, a controlled amplifier receiving each firstamplified signal, second means amplifying each color signalindividually, matrix bias means receiving each second amplified signaland applying same to the controlled amplifier of each other colorsignal, and means connecting the controlled amplifier output signals tothe color electrodes within the tube, said image screen including, afirst plate portion having a plurality of spaced openings therein, acontrol grid exposed within each opening, a second plate portion havinga plurality of corresponding spaced openings therein in register withthe first mentioned openings, and a discrete portion of material capableof emitting light of respective different colors exposed within eachopening, whereby upon electron bombardment the openings contain theelectrons to prevent their spreading to adjacent discrete portions thusavoiding color mixing.

References Cited by the Examiner UNITED STATES PATENTS 2,579,705 12/1951Schroeder 313-92.5 2,584,814 2/1952 Rosenberg et al. 3l3-81 2,842,6097/1958 Gretener 1785.2 2,863,939 12/1958 Jones 178-5.4

DAVID G. REDlNBAUGH, Primary Examiner. J. A. OBRIEN, Assistant Examiner.

1. IN A COLOR TELEVISION CIRCUIT AND IMAGE TUBE HAVING A SINGLE ELECTRONBEAM, AN IMAGE SCREEN, A PLURALITY OF CONTROL ELECTRODES CONTROLLINGELECTRON FLOW TO THE IMAGE SCREEN RESPONSIVE TO EACH COLOR SIGNAL, THEIMPROVEMENT INCLUDING, AMPLIFYING MEANS, FOR AMPLIFYING EACH COLORSIGNAL INDIVIDUALLY, A CONTROLLED AMPLIFIER RECEIVING EACH AMPLIFIEDSIGNAL, MATRIX BIAS MEANS RECEIVING EACH AMPLIFIED SIGNAL AND APPLYINGSAME TO THE CONTROLLED AMPLIFIER OF EACH OTHER COLOR SIGNAL, AND MEANSCONNECTING THE CONTROLLED AMPLIFIER OUTPUT SIGNALS TO THE COLORELECTRODES WITHIN THE TUBE.